/* Copyright (c) 2013, Ben Noordhuis <info@bnoordhuis.nl>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef UV_ATOMIC_OPS_H_
#define UV_ATOMIC_OPS_H_

#include "internal.h" /* UV_UNUSED */

#if defined(__SUNPRO_C) || defined(__SUNPRO_CC)
#include <atomic.h>
#define __sync_val_compare_and_swap(p, o, n) atomic_cas_ptr(p, o, n)
#endif

UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval));
UV_UNUSED(static long cmpxchgl(long* ptr, long oldval, long newval));
UV_UNUSED(static void cpu_relax(void));

/* Prefer hand-rolled assembly over the gcc builtins because the latter also
 * issue full memory barriers.
 */
UV_UNUSED(static int cmpxchgi(int* ptr, int oldval, int newval))
{
#if defined(__i386__) || defined(__x86_64__)
    int out;
    __asm__ __volatile__("lock; cmpxchg %2, %1;"
                         : "=a"(out), "+m"(*(volatile int*)ptr)
                         : "r"(newval), "0"(oldval)
                         : "memory");
    return out;
#elif defined(_AIX) && defined(__xlC__)
    const int out = (*(volatile int*)ptr);
    __compare_and_swap(ptr, &oldval, newval);
    return out;
#else
    return __sync_val_compare_and_swap(ptr, oldval, newval);
#endif
}

UV_UNUSED(static long cmpxchgl(long* ptr, long oldval, long newval))
{
#if defined(__i386__) || defined(__x86_64__)
    long out;
    __asm__ __volatile__("lock; cmpxchg %2, %1;"
                         : "=a"(out), "+m"(*(volatile long*)ptr)
                         : "r"(newval), "0"(oldval)
                         : "memory");
    return out;
#elif defined(_AIX) && defined(__xlC__)
    const long out = (*(volatile int*)ptr);
#if defined(__64BIT__)
    __compare_and_swaplp(ptr, &oldval, newval);
#else
    __compare_and_swap(ptr, &oldval, newval);
#endif /* if defined(__64BIT__) */
    return out;
#else
    return __sync_val_compare_and_swap(ptr, oldval, newval);
#endif
}

UV_UNUSED(static void cpu_relax(void))
{
#if defined(__i386__) || defined(__x86_64__)
    __asm__ __volatile__("rep; nop"); /* a.k.a. PAUSE */
#endif
}

#endif /* UV_ATOMIC_OPS_H_ */
